Microsoft Exchange Online introduces a new "Reject Direct Send" parameter to block unwanted Direct Send traffic. Public Preview is available now, with General Availability in September 2025. Admins can enable this feature using PowerShell. Review configurations and notify users. Learn more [here](https://techcommunity.microsoft.com/blog/exchange/introducing-more-control-over-direct-send-in-exchange-online/4408790).
Applies to: Exchange Online
Source: mc.merill.net — data via Merill Fernando's open archive (MIT).